Voltage responsive relay type quantizer for monitoring plural sources



United States Patent 'ice VOLTAGE RESPONSIVE RlELAY TYPE QUANTIZER FOR MONITORING PLURAL SOURCES Robert W. Bradley, Howard County, Md., :assignor to Powercon, Inc., Severn, Md., a corporation of Maryland Filed Dec. 20, 1966, Ser. No. 603,249

Int. Cl. H02h 3/12, 3/26 US. Cl. 317--31 4 Claims This invention relates generally to electric monitor devices, and more particularly it pertains to a relay type quantizer for signalling whether a given number of circuits are energized.

In the past, rather involved relaying has been necessary in order that the failure of one or more machines on a line, such as generators of a system of generators, will signal for redundant machines or generators to take their place in line and share the load.

It is an object of the present invention therefore, to provide an electrical circuit which insists on a given number of units on a line, and if less than this number should occur, the circuit will signal until the given number is restored.

Another object of this invention is to provide a circuit of this character which can be adjusted for different quantity sensitivities.

Still another object of this invention is to provide a quantizer operating on the difference between relay pullin and hold voltage which requires only a simple series sensing circuit for its operation.

Yet another object of the invention is to provide a quantizer which will accommodate additional units in its monitor series without any changes.

Other objects and attendant advantages of this invention will become more readily apparent and understood from the following detailed specification and single sheet of accompanying drawings.

In the drawing, reference numeral indicates generally a quantizer incorporating features of this invention. This quantizer 10 includes a voltage regulator comprising a Zener diode 12 and a series resistor 14 for deriving a constant voltage from an external supply 16. Any other regulator or other device for providing a constant voltage on connection 18, however, will serve equally well.

From connection 18, there is provided a return circuit to the common side 20 of a supply 16 consisting of first in series, a rheostat 22 and next a relay coil 24. This relay coil 24 is of the sensitive type and has an associated normally open contact 26 the purpose of which is to close a circuit from the supply 16 through a power type relay 28 back to the common side 20. The power type relay 28 can have several contacts. In the example, the relay 28 has two normally open contacts 30, 32 and a normally closed contact 34.

The first named contact 30 of the relay 28 is serially connected with a rheostat 36. This serial connection of contact 30 and rheostat 36 is in shunt with the relay coil 24. Terminals 38 and 40 provide for another shunt circuit across relay coil 24 exteriorly to the quantizer 10 as will be related.

The machines or generators A, B, C, etc. which it is desired to monitor, each have a non-restoring circuit breaker, not shown, each of which includes an auxiliary normally open contact 42A, B, C, X. These contacts 42A, B, C, X, are connected in series as shown across the terminals 38 and 40. Further, each open contact 42A, B, C, X has a shunt resistor 44 all being of equal value. A circuit breaker obviously must be closed for any unit, machine, generator etc. to be operative and consequently the associated auxiliary contact 42 will be closed at such time and short out its resistor 44.

Patented Apr. 29, 1969 The quantizer 10 is set up for operation in the following manner assuming that there are 5 units and breakers having the auxiliary contacts 42A, B, C, D and E and any three of the five are desired on at all times.

Two units, say A and B, are started manually, or optionally, the condition simulated by jumpers across their associated auxiliary contacts 42A and 42B. Both rheostats 22 and 36 are set for maximum resistance. Then rheostat 22 is gradually reduced in value until relay coil 24 picks up. It will chatter at this point, normally, but

if the adjustment is continued the relay coil 24 will stay picked up. This closes its contact 26 which actuates power relay 28 cutting in the rheostat 36. Relay 24 thus shunted will chatter tending to drop out. A small increase in voltage by reducing rheostat 22 will hold it in, however, just above the point of chatter.

Another unit, say C, is started or simulated on by a jumper across contact 42C. This reduces the external shunt across relay 24 and by reducing the resistance of rheostat 36, the relay 24 will positively drop out and stay out.

Should a breaker of an operating unit open due to a malfunction of the latter, another resistor 44 is thereby cut into the series of resistors 44 which shunt relay coil 24. This relay coil 24 will then pull in to close its contact 26. The power relay 28 thus actuated closes contacts 30 and 32 and opens contact 34. The latter two contacts may be used to initiate a starting circuit, not shown, for a gas engine, etc., of one of the standby units X, in this example D or E. Since the drop-out voltage of relay 24 is less than its pull-in voltage, the closing of contact 30 at this time does not cause relay coil 24 to drop out from shunt rheostat 36 thus cut-in until the additional resistor 44X of the standby unit X, has been cut in by the above-mentioned starting circuit and closing of associated breaker contact 42X.

The quantizer 10 is now in a condition of re-set to monitor any further malfunction of the units as recited above.

Obviously many modifications and variations of the present invention are possible in light of the above teachings. It is, therefore, to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

What is claimed is:

1. A monitor circuit for a plurality of electrical devices, comprising, relay means having a coil and coil actuated contacts, resistances associated with each said electrical device, contact means across each resistance closed when its respective device is operating and open when its respective device is non-operating, said resistances being in a series connection circuit, with said series connection circuit being connected across said relay coil, a constant voltage source, adjustable means for serially feeding electric current from said constant voltage source to said relay coil to energize said relay coil, adjustable means for bypassing current around said relay coil, one pair of said coil operated relay contacts being connected to open said bypassing current flow and other pairs of relay contacts for further utilization with said electrical devices.

2. In combination, a plurality of electrical generators, and a monitor circuit for said plurality of electrical generators consisting of relay means having a coil and coil actuated contacts, resistance means associated with each said electrical generator, contact means across each resistance means closed 'when its respective electrical geneartor is operating and open when its respective electrical generator is non-operating, said resistance means being in a series connection circuit, with said series connection circuit being connected across said relay coil, a costant voltage soure, adjustable means for serially feeding electric current from said constant voltage source to said relay coil to energize said relay coil, adjustable means for bypassing current around said relay coil, one pair of said coil operated relay contacts being connected to open said bypassing current flow and other pairs of relay contacts for further utilization with said electrical generators.

3. In combination, a source of regulated voltage, resistance means and relay means serially connected across said source of regulated voltage, a plurality of serially connected resistances of equal value connected across said relay means, a normally closed contact operable by said relay means, a second resistance means, said contact and second resistance means being serially connected across said relay means, a plurality of circuit breakers each having an auxiliary contact and a load contact, said circuit breakers each being of a type which will open both auxiliary and load contact with associated load malfunction, with each auxiliary contact being connected across one of the plurality of equally valued resistances.

4. In combination, a source of voltage to be regulated, resistance means and relay means serially connected across said source of regulated voltage, a plurality of serially connected resistance means of equal value connected across said relay means, a normally closed contact operable by said relay means, other resistance means, said contact and other resistance means being serially connected across said relay means, a plurality of circuit breakers each having an auxiliary contact and a load contact, said circuit breakers each being of a type which will open both auxiliary and load contact with associated load malfunction, with each auxiliary contact being connected across one of the plurality of equally valued resistance means.

References Cited UNITED STATES PATENTS JOHN F. COUCH, Primary Examiner.

R. V. LUPO, Assistant Examiner.

US. Cl. X.R. 307-65, 87 

1. A MONITOR CIRCUIT FOR A PLURALITY OF ELECTRICAL DEVICES, COMPRISING, RELAY MEANS HAVING A COIL AND COIL ACTUATED CONTACTS, RESISTANCES ASSOCIATED WITH EACH SAID ELECTRICAL DEVICE, CONTACT MEANS ACROSS EACH RESISTANCE CLOSED WHEN ITS RESPECTIVE DEVICE IS OPERATING AND OPEN WHEN ITS RESPECTIVE DEVICE IS NON-OPERATING, SAID RESISTANCES BEING IN A SERIES CONNECTION CIRCUIT, WITH SAID SERIES CONNECTION CIRCUIT BEING CONNECTED ACROSS SAID RELAY COIL, A CONSTANT VOLTAGE SOURCE, ADJUSTABLE MEANS FOR SERIALLY FEEDING ELECTRIC CURRENT FROM SAID CONSTANT VOLTAGE SOURCE TO SAID RELAY COIL TO ENERGIZE SAID RELAY COIL AJUSTABLE MEANS FOR BYPASSING CURRENT AROUND SAID RELAY COIL, ONE PAIR OF SAID COIL OPERATED RELAY CONTACTS BEING CONNECTED TO OPEN SAID BYPASSING CURRENT FLOW AND OTHER PAIRS OF RELAY CONTACTS FOR FURTHER UTILIZATION WITH SAID ELECTRICAL DEVICES. 